What's "shifting a file" supposed to do? From your description it sounds that you only need to shift a little inside some kind of loop. Please provide more details.
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JonNov 29 '11 at 11:19

Want to preserve the data on the shift back. Should be identical as before I performed the shifting.
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Jason CaldwellNov 29 '11 at 11:20

I think @Jon is right, just loop through your file & create a new one in the process. Dont forget to check for loss of data at word boundaries. (or however large a data item you can shift on!)
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NWSNov 29 '11 at 11:28